Motor control system



Jan. 7, 1936.

F. M. PARKS MOTOR CONTROL SYSTEM I Z a Fi Z 12 WITNESSES I INVENTOR Fred M. Parks 1 Patented Jan. 1, 1936 2,027,247

LUNITED STATES PATENT OFFICE MOTOR CONTROL SYSTEM Fred M. Parks, Murrysville, Pa., assignor to Westinghouse' Electric & Manufacturing Company, East Pittsburgh, Pa, a corporation of Pennsyl- Vania Application April 14, 1934, Serial No. 720,598

6 Claims. (Cl. 172239) My invention relates to motor control systems mechanically coupled to a transmitter lot a secand has special reference to systems'ot the sond synchro-tie system 15. The receiver 9 01 called synchronous tie" type. the synchro-tie system I6 is also coupled to the One object of my invention is to control the opregulator through the mechanical gearing l3. eration of a motor responsive to the movement, As is well known, for a synchro-tie system or 5 or variations in movement, of an element of a. deconnection; the receiver motor follows movevice that is to be controlled by the motor. merits of the transmitter motor very exactly Another object of my invention isto control the which therefore means that any variation of the starting and stopping oi a motor in response to height of the tank 2 will be reflected by a corvariations in position of an element oi a device responding movement of the member ll actuated 10 the operation oi. which is to be controlled by the by the receiver 3 through the gear mechanism 1 0. motor. The member I I is coupled to a mercoid switch A further object of my invention is to control l2 which is pivotally mounted on a vertically the operation of a motor driving a device to commovable member 14. Any vertical movement oi l5 pensate for certain changes in operation of the the member II will initiate the operation of the device. I motor 6 which thereupon will operate the trans- A still further object of my invention is to mitter 5' and the throttle valve 1. The receiver provide a control for a motor wherein the change motor 9, as is well known for synchro-tie" conin position, or the starting and stopping of the nections, follows the transmitter motor 5, thereby motor, will correct for the change in the opmoving the vertically movable member through 20 eration of the device driven by the motor which the gear mechanism IS in such a direction'as to initiates such variation in position'or starting and r u t e e d Sw 12 t e Po stopping of the motor. shown in Fig. 1. In this position the energizing A more specific object of my invention is to circuit for the motor 6 is interrupted and the ac- 26 maintaimior example, the top of a gas accumutuatidn of the throttle valve 1 is halted. If the lator tank, where the supply is variable, in a correction was not sufficient at o Operation Of definite position by controlling a throttle valve h motor 6, and h p 2 continues to move in in the demand line; or to maintain a definite tenits i al dir ti n i. m t th cycle f psion on a strip of paper or steel between sections eretion just explained is rep again end 30 r -011 t d again, if necessary, thereby effecting the desired 30 Other objects and advantages will become more correction for the position of the throttle valve apparent from a study of the following specificain small increments until the limit of travel for tion when considered in conjunction with the e Va ve has been reached. accompanying drawing, inwhich: To state the foregoing operation more in detail,

Figure 1 is a diagrammatic showing of the let it be assumed that the demand on the de- 35 novel features of my invention as applied to a m n lin r pipe 8 s su as to aus a low r n gas accumulator tank using two synchro-tie' I of the top2 of the tank H. The top 2 is coupled units or systems; and to a sheave 2i on the shaft of the transmitter I Fig. 2 is a schematic showing of certain met u the a l T provide for the p p 40 hanical features of my invention, used with cooperative action between the top 2, the cable gas accumulator tank, whenonly one syn'chro- 22, and t e sh ave a Weight 23 is hung t tie unit or system is used. one end of the cable that traverses one of the Referring more particularly to Fig. l of the sheaves 24 of a crown block in the installation, drawing, a gas accumulator tank I! comprises a is wound to the extent of several turns on the movable top 2 and a fixed base is, The movable sheave 2i, traverses a second sheave 24 in the top 2 is suitably mechanically coupled to the crown block, and has its other end attached to transmitter l of a synchro-tie" system I5.- The the top 2. receiver 3 of the "synchro-tie system is me- The synchro-tie systems I5 and [6 are conchanically coupled to a regulator 4 whereby the nected by single phase stator windings for the Sill-demand that may be put on the supply of gas respective motors shown to a suitable source 01 in the tank may be regulated by the throttle valve alternating cu t indi at d y the us s 9.

1. The throttle valve 1 is mechanically coupled The secondary windings of the respective transto a motor 6 which may be operated either to open mitters and receivers are interconnected so that.

or to close the throttle valve, as will be pointed neither the rotors of the transmitters nor the out more in detail hereinafter. The motor 6 is receivers will rotate under normal conditions.

the vertically movable member I4 and an energizing circuit is established for the motor 6 through the lower contact member 26 and the contact member 21 of the mercoid switch [2.

The motor 6 shown is a split-series motor, al.-

though any other reversible motor would be satisfactory and, upon the movement of the mercoid switch I2 just explained, will operate in such a direction as to shut ofi the gas moving I into the demand line 8.

Operation of the motor 6 drives the shaft of the transmitter 5 through ,the gearing 28, The synchro-tie system I6 is similar in every respect tothe synchro-tie system [5 and in consequence the armatureof the receiver 9 will be rotated exactly the same amount that the armature of the transmitter 5 is rotated by the motor 6. The vertically movable member, I4 is thus moved downwardly through the gearing I3 and since such movement moves the pivot point 25 downwardly, the mercoid switch I2 will be tilted to the position shown'in both figures, whereupon the operation of the motor 6 ceases. If the top 2 continues to move downwardly, the cycle of operation justexplained is repeated again and again, if necessary, until the'limit'of travel for the" member. I4 is reached at which point the throttle valve 'Iis completely closed, preventing the flow of any gas into the demand line or p pe 8.

If the demand decreases, thus causing a rise in the level of the tank 2, the mercoid switch I2 will be tilted towards the left and the motor 6 will be caused to operate to open the throttle valve I. The vertically movable member I4 will thereupon be actuated in an upward direction to interrupt the energizing circuit for the motor The foregoing control system for the gas accumulator tank I! thus provides an accurate,

reliable and cheap means of controlling the posi- .need not be located at a remote place but can be positioned at the tank, there is no real need for' tion of the top 2 of the-tank I1. 7

'In some installations, where the receiver 3 a synchro-tie connection such as shown at I5. In such case, as is shown in Fig. 2, the movement of the top 2 may influence the position of the mercoid switch directly through a mechanical coupling. The regulator 4 with regard to the vertically movable member I4 will, however, still be controlled by the synchro-tie connection I6, shown in Fig. 1. The control of the position of the top 2 may thus be very economically effected without the .synchrotie connection I5.

The control system hereinbefore described is 7 not limited to the control of the position of the top of a gas accumulator tank but has general application and may, of course, be readily used in the paper mill industry where two or more machines are to be controlled so as to follow exactly theoperations of a main machine or a Icontrol motor or a pilot means.

My system of control is also of utility in the steel industry where a strip of material .being rolled is to be rolled under a fixed tension.

Those skilled in the art after having had the benefit of the teachings of my invention can readily apply my invention to the apparatus I have suggested and there is, therefore, no need to show in detail how my system of control might be used with such other apparatus. I wish, therefore, to be limited only by the claims appended hereto and any pertinent prior art.

I'claim as my invention:

1 In a system of control, in combination, a member the position of which is to be controlled, a synohro-tie system including a transmitter motor and a receiver motor, said transsecond synchro-tie system including a transmitter motor and a receiver motor, a reversing motor connected to aid in positioning said 'ment for the slidable member from the other receiver motor.

2. In a system of control, in combination, a

member the position of which is to be controlled,

a synchro-tie system including a transmitter motor and a receiver motor, said transmitter motor being coupled to the member, a second synchro-tie system including a transmitter motor and a receiver motor, a reversing motor connected to aid in positioning said member in one or the other direction and also coupled to,

drive said last-named transmitter motor, a 'slidmitter motor being coupled to the member, a a

able member connected to the receiver motor of said switch being adapted to'co'ntrol the direction of rotation of said reversible motor..

3. In a system of control, in combination, a

member the position of which is to be controlled,

a reversible motor coupled to aid inpositioning said member in one or the other direction, a synchro-tie system including a transmitter motor and a receiver motor, said transmitter motor being coupled tosaid reversible motor, a slidable member coupled to said receiver motor, a switch pivotally mounted on the slidable member and adapted to control the direction of rotation of said reversible motor, and means adapted to tilt said pivotally mounted switch in response to movements of the first-named member.

4. In a system of control, in combination, devices whose operating characteristics are to be held within a certainrange relative to each other, a synchro-tie system includingatransmitter motor and a receiver motor, said transmitter motor being coupled to be operable by variations of said certain range,-a second synchro-tie system including a transmitter. motor and a receiver motor, a reversible motor adapted to produce effects to counteract variations in said certain range, a slidable member, a switch pivotally mounted on said member and adapted to control the direction of operation of said reversible motor, andcoupling means for effecting tilting of said switch from one receiver motor and a sliding movement from the other receiver motor.

5. In a system of control, in combination, devices whose operating characteristics are to be held within a certain range relative to each other, a synchro-tie system including a transmitter motor and a receiver motor, said transmitter motor being coupled to be operable by variations of said certain range, a second synchro-tie system including a transmitter motor and a receiver motor, a reversible motor adapted to produce eflects to counteract variations in said certain range, a slidable member connected to the receiver motor of the second named synchro-tie system, and a switch pivotaily mounted on the slidable members and connected to be tilted by the receiver motor of the first-named synchro-tie system,

be driven by said reversible motor, a slidable 10 member adapted to be slidably operated by said receiver motor, a switch pivotally mounted on the slidable member and adapted to control the direction of rotation of said reversible motor,

and means adapted to tilt said switch in re- 15 spouse to variations in the operating characteristics relative to each other and said devices.

' FRED M. PARKS. 

